Atherosclerosis is the leading cause of morbidity and mortality worldwide. It is a complex disease initiated and propagated by lipoprotein deposition and inflammation. Later stages of atherosclerosis are characterized by progressive deposition of calcium in the coronary arterial vessel-wall. Histopathology, computed tomography and intravascular ultrasound studies have confirmed that the extent of coronary calcification is closely correlated to the atherosclerosis plaque burden.
A cardiac tomography (CT) based coronary artery calcium (CAC) scan is a non-contrast-enhanced, three dimensional imaging technique that has been introduced as a non-invasive, low-radiation method for the assessment of the overall coronary arterial atherosclerotic burden, by quantifying calcium in the coronary vasculature. CAC has been validated to be independent of, and additive to, the Framingham Risk Score (FRS) in predicting major cardiovascular events. CAC is also considered safer and more appropriate for the primary prevention setting than invasive modalities, such as intravascular ultrasound (IVUS), and non-invasive and high-radiation modalities, such as CT angiography.
A three dimensional CAC image volume contains a large amount of clinically relevant information, such as the geometric and morphologic characteristics of each calcific lesion, which can be of high diagnostic and therapeutic value. However, current measurements of CAC, such as the Agatston score and the volume score, only quantify the whole-heart calcium burden.